Method and apparatus for forming covered index tabs on sheets



l 29, 1958 'L. T. KEENAN 2,845,010

METHOD AND APPARATUS FOR FORMING COVERED INDEX- TABS ON SHEETS Filed July 6, 1955 5 Sheets-Sheet 1 n V INVENTOR.

l Z gyciffleena/m July 29, 1958' L. T. KEENAN METHOD AND APPARATUS FOR FORMING COVERED INDEX LABS ON SHEETS Fild July 6, 1955 5 Shets-Sheet 2 METHOD AND APPARATUS FOR FORMING COVERED INDEX TABS ON SHEETS Filed July 6, 1955 July 29, 1958 L. T. KEENAN m M AW W m (I A A E W r .8: @N NM July 29, 1958 "r. KEENAN METHOD AND APPARATUS FOR FORMING- COVERED INDEX TABS on SHEETS Filed July 6, 1955 5 Sheets-Sheet 4 I v INVENTOR, Z Zgyd 13K ee mm BY L. 1'. KEENAN METHOD- AND APPARATUS FOR FORMING COVERED INDEX TABS ON SHEETS Filed July. 6, 1955 5 Sheets-Sheet 5 I INVENTOR. dfjleenam 921/014! M/ 'onw he 4 Zlo BY WNW United States Patent Ofiice 2,845,010 Patented July 29, 1958 METHOD AND APPARATUS FOR FORMING COVERED INDEX TABS ON SHEETS Lloyd T. Keenan, Oak Park, Ill.

Application July 6, 1955, Serial No. 520,204

27 Claims. (Cl. 93-1) This invention relates to the application of index tab covers and more particularly to a novel continuous method and apparatus for forming covered index tabs on sheets or the like.

As is well known, special index sheets are commonly used in reference works and other publications and in file drawers or the like as dividers for segregating difcferent subject matter, and such sheets are commonly provided with index tabs which project outwardly from the edges of the sheets with printed indicia or other identifying legends thereon. Since these index tabs are subject to repeated and severe use, it is desirable to protect them with a suitable covering material such as a transparent or colored plastic, e. g., cellulose acetate film or the like. Normally, the protective cover element or jacket is in the form of a folded piece of plastic material fitted over the edge of the sheet and permanently bonded to both sides thereof.

Heretofore, the application of protective cover elements or jackets to the tabs of index sheets or the like has involved tedious manual operations. For example, it is customary to provide the folded covers or jackets as separate elements and an operator takes each index sheet in turn, fits a folded cover over the tab of the index sheet, and then inserts the assembled cover and sheet in a press for permanent bonding of the cover to the tab. Obviously, such manual operations are costly and time consuming but no satisfactory automatic mechanism for carrying out this operation has been suggested heretofore because of the difficulties involved in handling a multiplicity of small pieces of folded plastic material and in aligning such preformed cover elements in proper position on the projecting tabs of the index sheets. Small pieces of plastic material such as cellulose acetate are difficult to handle because the material is sensitive to temperature change, frequently has pronounced curling tendencies, is prone to accumulate static electricity charges, and is generally difficult to manipulate by automatic machine techniques.

As will hereinafter appear, the present invention solves certain of these difliculties by providing the protective cover elements or jackets in a unique interconnected strip form which can readily be handled by automatic machinery and from which individual cover elements can be severed as required. The invention also involves the novel concept of attaching an individual protective cover element to the straight edge of each sheet prior to tabcutting of the sheet to form a projecting tab thereby further facilitating and simplifying the entire operation.

Accordingly, one object of the present invention is to provide a novel and improved method for the continuous formation of covered index tabs on sheets or the like.

A further object of the invention is to provide a novel automatic apparatus for carrying out the foregoing method.

Another object of the invention is to provide novel automatic means for the application .of index tab covers which eliminates manual handling of individual cover elements.

An additional object of the invention is to provide novel automatic means for effecting alignment and registration of a folded index tab cover with the edge of a sheet.

Other objects and advantages of the invention will become apparent from the subsequent detailed description taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is an overall perspective view of an apparatus comprising one specific embodiment of the invention;

Fig. 2 is an enlarged fragmentary perspective view of the assembly and tab cutting portions of the apparatus;

Fig. 3 is a top plan view of an enlarged scale showing an adjustable connection between certain portions of the apparatus;

Fig. 4 is a diagrammatic perspective view of another portion of the apparatus;

Fig. 5 is a fragmentary view of the cover strip utilized in the apparatus;

Fig. 6 is a top plan view of the portions of the apparatus shown in Fig. 2;

Fig. 7 is an'enlarged transverse view partly in section and partly in elevation as taken substantially along the line 77 of Fig. 6;

V Fig. 8 is a fragmentary elevational view of a detail of the apparatus showing part of the sheet transfer mechanism; and

Figs. 9 and 10 are fragmentary corner views of a sheet showing successive stages in the application of a cover element and the formation of a covered tab on the edge of the sheet.

In its method aspects, the invention involves the steps of (1) forming a continuous elongated longitudinally folded cover strip with incomplete transverse cuts extending partially across the width of the strip at longitudinally spaced intervals to provide a plurality of folded cover elements interconnected in end-to-end relation by restricted uncut connecting portions along the folded edge of the strip, (2) feeding a plurality of sheets one-by-one to an assembly station, (3) feeding the aforementioned strip stepwise to the assembly station and in timed relation to the feeding of the sheets, (4) aligning the terminal cover element at the leading end of the strip in straddled relation over the edge of the particular sheet at the assembly station, (5) adhering the terminal cover element to the sheet by means including the application of pressure, (6) severing the terminal cover element at the leading end of the strip from the remainder of the strip, preferably simultaneously with the application of pressure, and (7) cutting or trimming the edge of the sheet with its attached cover element to form a new edge with a covered tab projecting outwardly therefrom.

For an overall brief description of the apparatus, which comprises one illustrative embodiment of the invention, reference is first made to Figs. 1 and 2 of the drawings wherein the cover strip and feeding mechanism is designated generally at 11 and is mounted on a support or table 12 having wheels 13 for movement along a track 14 for the purpose hereinafter described. A paper feeding machine, designated generally at 16, is arranged to feed individual sheets from a stack 17 one-by-one down an inclined chute 18 to one end of an elongated cover applying and tab forming machine designated generally at 19. The latter machine includes an elongated bed portion 21 (Fig. 2) having located therealong a receiving station A at one end of the bed 21 which receives the individual sheets from the sheet feeding unit 16, an assembly station B at which the leading end portion of the continuous cover strip from the unit 11 is secured by means of a movable pressure applying member in strad- 1 mm died relation over the edge of a sheet and is severed from the remainder of the strip, a tab forming station C where a die-cutting or trimming operation is performed on the edge of each sheet to form a projecting covered tab, and a discharge station D at the opposite end of the bed 21 at which point the completed index sheet is discharged from the machine. As hereinafter described in detail, the ma chine 19 is equipped with suitable transfer means for engaging each successive sheet and moving it in intermittent stepwise fashion through the successive stations A, B, C, and D. In addition, the operating mechanism of the unit 19 is synchronized by suitable controls with the operation of the units 11 and 16 so that the stepwise feeding of the cover strip from the unit 11, the feeding of individual sheets from the unit 16, the operation of the pressure applying member at station B, and the operation of the die-cutter at station C are all carried out in correlated and timed relation so as to obtain a continuous coordinated operation of the entire apparatus.

Referring now to the different portions of the apparatus in somewhat more detail, the strip former and feeder unit 11 is a device of a well known type, such as manufactured by the Ohm Company of Minneapolis, Minnesota, which unwinds a continuous strip 22 of tab covering material such as cellulos acetate or the like from a supply roll 23, folds the strip in half longitudinally thereof, and then die-cuts the folded strip to any desired configuration. Since the exact details of this unit 11 are not involved in the present invention, a brief description of this portion of the apparatus will sufiice. In Fig. 4 the unit 11 is shown diagrammatically and it will be seen that the strip 22 is drawn by internal roller means (not shown) into the converging throat 23 of a conventional folder where the strip is folded in half longitudinally and is then passed through an electrically heated zone 24 for permanently setting the longitudinal fold of the strip. The folded strip is then passed through a die-cutting means 26 to inpart the desired configuration to the strip.

Heretofore, in the use of such machines, the folded strip has simply been severed by the means 26 into a multiplicity of individual folded cover elements or jackets of desired length and shape. However, for purposes of the present invention the die in the die-cutting means 26 is constructed to provide a continuous folded strip of the form best seen in Fig. wherein the strip is designated generally at 27 and has a plurality of incomplete transverse cuts 28 extending partially across the width of the folded strip and spaced longitudinally of the strip. In effect, the completed strip 27 consists of a plurality of folded cover elements 29 which are integrally interconnected in end-to-end relation by restricted uncut connecting portions 31 along the folded edge of the strip. Moreover, the corners of the individual cover elements 29 are rounded, as at 32. An elongated tubular conduit 33 extends from the outlet side of the unit 11 for receiving the preformed strip 27 as it is ejected from the unit 11 and guiding the same to the assembly station of the apparatus, as hereinafter described.

The sheet feeding unit shown at 16 (Fig. l) is likewise a conventional device, in this case a standard Davidson paper feeder, so that only a brief explanation will be required. The sheet feeder has an upright frame 34 which supports the stack 17 of horizontally disposed sheets. The machine has means for transferring the sheets oneby-one from the stack 17 and feeding them down the inclined chute 18 to the receiving station A of the unit 19. In this case, the means for picking 01f individual sheets from the top of the stack 17 comprises a plurality of suction tubes 36 connected to a vacuum pump 37 driven by a motor 38. Driven roller means (not shown) are also provided within the chute 13 to assist in conveying the individual sheets one-by-one to initial position on the flat horizontal bed 21 at the receiving station A thereof (Fig. 2). A pair of frictional drive wheels 39 connected to the driving mechanism of the machine 19 then move the individual sheets into position for transfer to the assembly station B as described below.

The unit 19, at which the assembly and tab cutting operations are performed, may comprise any suitable type of intermittent conveying mechanism for moving the sheets in stepwise fashion between the successive stations of the apparatus. The details of the conveying mechanism are not important for purposes of the present inven tion so that once again only a brief description of this portion of the apparatus is required for an understanding of the invention. In the illustrated embodiment, the elongated bed 21 of the unit 19 is provided with a pair of parallel slots 41 through which a plurality of upright pusher elements or fingers 42 are projected from the underside of the bed 21 for engaging the trailing edge of each successive sheet.

Referring to Figs. 7 and 8, it will be seen that in this instance the pusher elements 42 are arranged in three pairs spaced longitudinally of the bed 21 for simultaneously engaging the rear edges of three successive sheets, as designated at'43, 44 and 46. The upright pusher elements 42 are mounted for vertical reciprocating movement in a plurality of supports 47 on an elongated carriage 48 which is arranged for longitudinal reciprocating movement below the bed 21 and is actuated by a rod 49 connected to the drive mechanism of the device. The lower end of each pusher element 42 is pivotally connected to one portion of a double bell crank arrangement 50 rockable about an axis 51 and having its other portion pivotally connected to an elongated link 52 parallel to the carriage 48. For actuating the several bell crank arrangements 50 in unison, the link 52 has a bracket 53 depending rigidly therefrom and connected to an actuating rod 54 which extends to the driving mechanism of the machine. Thus, it will be seen that the main driving mechanism of the machine, acting through the rods 49 and 54, effects reciprocating back and forth movement of the carriage 48 parallel to the bed 21 and at the same time the vertically movable pusher elements 42 are projected upwardly and retracted downwardly through the interlocked bell crank devices in a coordinated manner for moving three sheets at a time in stepwise fashion along the bed 21.

In the position seen in Fig. 8, the pusher elements 42 are in upwardly projected position and are in the process of moving the sheets 43, 44 and 46 to the right, the sheet 43 being transferred from the receiving station A to the assembly station B, the sheet 44 being transferred from the assembly station B to the tab cutting station C, and the sheet 46 being transferred from the tab cutting station C to the discharge station D. At the right-hand end of the stroke, it will be understood that the carriage 48 begins to move in the opposite direction and almost immediately the pushers 42 are retracted downwardly below the surface of the bed 21 by the action of the mechanism 5051-5253-54 so that the pushers can pass beneath and clear the next group of sheets on the bed. As the carriage 48 reaches the left-hand end of its stroke, the pushers 42 are again projected upwardly through the slots 41 and are brought into engagement with the trailing edges of the next group of sheets for stepwise movement to the right in the manner shown in Fig. 8. This sequence is repeated continuously so that for each complete reciprocation of the carriage 48 a set of three sheets is advanced one station through the process.

As briefly mentioned above, the tubular conduit 33 (best seen in Fig. 3) extends from the outlet side of the strip former and feeding unit 11 and guides the advancing cover strip 27 at an angle toward the side of the bed 21 of the unit 19 slightly to the rear of the assembly station B. Thus, the strip 27 as it emerges from the guide tube 33 converges with the sheet transfer line along the horizontal bed 21. At this juncture a combined spreader and guide device, designated generally at 56, is mounted alongside the bed 21 for spreading the leading end of the folded cover strip 27 and aligning the same in straddled relation over the adjacent longitudinal edge of the particular sheet at the assembly station. This device, as best seen in Figs. 2, 6 and 7, is in the form of an elongated folded member having a laterally disposed generally U-shaped cross section (Fig. 7) with transversely spaced upper and lower wall portions 57 and 58, respectively. The lower wall portion 58 overlies the bed 21 at the side edge thereof, and the upper wall portion 57 is flared upwardly, as at 59 in Fig. 2, at the rearward end of the guide member to facilitate axial entry of the side edge portion of each sheet in guided relation between the wall portions 57 and 58 as the sheet is advanced from the receiving station A to the assembly station B.

Extending angularly outwardly from the same rearward end of the guide member 56 in the direction of the strip 27 is a generally pointed spreader element 61 Which extends into the leading end of the strip 27 between the respective halves thereof for spreading the folded strip in response to longitudinal feeding movement of the strip against the stationary element 61. As seen in Fig. 6, the spreader 61 merges in a smooth continuous manner with the outermost folded edge between the walls 57 and 58 so that the spread-apart strip 27 as it is fed forwardly straddles the exterior of the spaced guide walls 57-58 while the cooperating sheet is disposed in sandwiched relation in the space between the walls 5758 (Fig. 7). Continued advancement of the strip 27 along the guide member results in ejection of the leading end of the spread-apart strip beyond the forward end of the guide with the result that the spreadapart strip is released and automatically contracts into straddled position embracing the edge of the sheet. A longitudinally adjustable flange member 62 (Fig. 6) is disposed along the folded edge of the strip 27 intermediate the outlet end of the tube 33 and the spreader 61 for holding the strip laterally against the spreader and guide 61-56 and thereby insuring proper coaction of the spreader during advancement of the strip 27.

For permanently adhering the terminal cover element at the leading end of the strip 27 to the sheet at the assembly station in the desired predetermined location thereon, a suitable pressure applying means 63 is mounted alongside the bed 21 at the assembly station E. Although the pressure applying means may obviously have any suitable construction, the press illustrated in this case comprises an elongated lower arm or beam 64 having rockably mounted thereon an upper pressure applying arm or lever 66 with a central pivotal mounting as at 67. The end of the lever arm 66 which is remote from the bed 21 has a pin and slot operating connection 68 with the upper end of a vertically movable piston rod 69. The lower end of the piston rod 69 is rigidly afiixed to a piston (not shown) which is slidable in the usual manner in a fixed cylinder 71, the latter being rigidly supported in depending relation from the beam 64 by means of a plurality of supporting rods 72. The opposite end of the rocker arm or lever 66 carries an electrically heated platen 73 adapted to coact in clamping relation with a complementary stationary platen 74 on the edge of the bed 21, the platen 74 likewise being electrically heated.

When the sheet has been delivered in position at the assembly station B and the terminal cover element at the leading end of the strip 27 has been aligned in straddled relation at the edge of the sheet as described above, the piston and cylinder mechanism 71 is automatically actuated by suitable control means to rock the pressure applying arm 66 downwardly so as to clamp the registered cover element and sheet under substantial pressure between the heated platens 73 and 74. The inner surfaces of the folded cover strip 27 being coated with .a

heat activatable adhesive material, it will be understood that a permanent bond is obtained between the terminal cover element of the strip 27 and the corresponding sheet under the influence of heat and pressure from the platens 7374. For severing the terminal cover element from the remainder of the strip simultaneously with the bonding action of the platens 73-74, a small knife blade 76 (Fig. 7) is adjustably mounted at the side of the platen 73 and is adapted to sever the adjacent connecting portion 31 as the movable platen 73 is brought into clamping engagement with the terminal cover element. Of course, the corresponding edge of the sheet is likewise slit to a slight extent during cutting of the connecting portion of the strip. After the movable platen 73 has been clamped against the strip for the proper length of time to effect bonding, the piston and cylinder mechanism 71 is again automatically energized for rocking the arm 66 in the opposite direction and releasing the clamping action. Thus, the sheet at the assembly station E now has its own individual cover element permanently bonded to the edge thereof and is ready to be transferred to the tab forming station C by means of the pusher elements 42 in the manner heretofore described.

'Prior to the application of pressure by the platens 7-374 as just described, it is quite important that the terminal cover element at the leading end of the strip 27 be in snug engagement with the edge of the sheet. To insure this condition, the invention preferably includes means at the assembly station for urging the cover element and the sheet laterally toward each other. As shown in Figs. 6 and 7, this is accomplished in the present embodiment by means of a grooved back-up roller -'77 which is adjustably mounted in a block 78 for movement away from and toward the strip 27 by means of a threaded adjusting member 79. The roller 77 engages the outside of the folded edge of the strip 27 for preventing lateral movement thereof. A bracket 81 secured to the outer end of the rocker arm 66 carries an angularly depending pusher element '82 having a resilient finger 83 with a pad of rubber 84 or the like adapted to frictional'ly engage the upper surface of the sheet. As will be evident from Fig. 7, when the outer end of the arm 66 is rocked downwardly, the rubber pad 84 engages the sheet at the assembly station just prior to clamping engagement of the platen 73 with the-cover element thereby urging the sheet laterally to the left, as viewed in Fig. 7, toward the backup roller 77 and thereby insuring snug engagement between the longitudinal edge of the sheet and the inside of the folded edge of the cover element just before application of bonding pressure.

Following the bonding and severing operation at the assembly station B and the release of the movable pressure platen 73, the sheet transfer mechanism including the pusher elements 42 automatically transfers the sheet with its attached individual cover element to the tab forming station C. During this longitudinal movement of the sheet along the bed 21, the sheet is urged into aligned engagement along its opposite longitudinal edge with an upright guide flange 86 on the bed 21 by means of a plurality of angularly disposed roller elements 87 (Fig. 2) which are pivotally suspended from an overhead elongated support 88. The roller elements 87 being in engagement with the upper side of the sheet and being disposed at an angle between the opposite longitudinal edges of the bed, it will readily be seen that during forward advancement the sheet is also urged laterally to the right, as seen in Fig. 2, in edgewise abutment with the side flange 86. During the transfer of the sheet from the assembly station E to the tab forming station C, the sheet is held flatwise against the bed by means of a plurality of resilient arms 89 which extend longitudinally of the bed from adjustable supports 90.

At the assembly station C, a conventional die-cutting mechanism 91 is mounted for trimming the edge of the sheet and its attached cover element. Thus, a pair of coacting dies 92 (Fig. 6) are carried at the end of suitable rocker arms 93 mounted on a longitudinally extending rock shaft 94. The rock shaft 94 is actuated by a crank arm 96 at one end thereof which is in turn interconnected with the main drive mechanism of the unit 19 in a conventional manner (not shown). When the sheet and its attached cover element is in position at station C, the die-eutting mechanism 91 is actuated through the arm 96 and the dies 92 are lowered into cutting engagement with the longitudinal edge of the sheet thereby trimming the entire edge of the sheet and its attached cover element to form a new edge with a projecting covered tab. The action of the angularly arranged rollers 87 insures proper alignment of the sheet prior to operation of the die-cutter at station C, and this alignment effect is further supplemented by a pair of angularly extending resilient pusher rods 97 extending outwardly from the dies 92 and carrying rubber pads 98 or the like for frictionally engaging the sheet and urging the same laterally toward the flange 86 just prior to engagement of the dies 92 with the sheet.

Following the die-cutting operation at station C, the sheet is again advanced by the pushers 42 to the discharge station D at the end of the bed from which the sheets are successively discharged by means of a roller 99.

As previously mentioned, the driving mechanism for the apparatus involves suitable control means for synchronizing the operation of the various units to obtain the desired timed sequence of operations. The main drive shaft of the unit 19 is designated at 101 in Fig. 1 and is driven from the main drive motor (not shown). By means of suitable geared connections and conventional mechanical movements, the details of which are unimportant for purposes of the present invention and will readily be comprehended by those skilled in the art, the sheet transfer mechanism including the carriage 48 and the linkage 52-53 is driven from the shaft 101 in the manner heretofore described. Likewise, the rock means 9496 for the die-cutting means 91 is operated by suitable driving connections to the shaft 101. Synchronization of the sheet feeding unit 16 with the operation of the unit 19 is achieved by a direct mechanical connection in the form of an elongated link 102 (Fig. 1) which interconnects a rotating member 103 on the unit 19 with an oscillating arm (not shown) on the unit 16. A limit switch 104 is mounted adjacent the rotating member 103 for actuation thereby and has an electrical circuit connection with a motor 106 which drives the strip forming and feeding unit 11 through a single revolution clutch 107 and a sprocket and chain drive 108. Thus, for each revolution of the member 103 on the unit 19, which corresponds to one complete cycle of the sheet transfer mechanism and die cutting mechanism, the sheet feeder 16 is actuated to feed onesheet to the unit 19 and the strip former 11 is actuated to feed the preformed strip ahead a single increment in timed relation to the feeding of the sheets.

The movable pressure applying arm 66 carrying the platen 73 is operated by the piston and cylinder arrangement 71 as previously described. To synchronize this portion of the apparatus with the movement of the sheets and the cover strip, another limit switch 109 (Fig. 8) is mounted for actuation by the forward end of the carriage 48 adjacent the discharge end of the bed 21. This switch 109 is in an electrical circuit with a solenoid valve (not shown) for controlling admission of air or other actuating fluid to the cylinder 71, and a time delay relay or bellows arrangement (not shown) is also provided for holding the arm 66 in clamping position for a predetermined time interval before release thereof. Thus, as the carriage 48 reaches the right-hand end of its travel (as viewed in Fig. 8) which corresponds to the positioning of a new sheet and a new terminal cover element in registered relation at the assembly station B, the limit switch 109 is actuated thereby causing the pressure arm 66 to move down for bonding the cover element to the sheet and simultaneously severing the cover element from the rest of the strip. Of course, the operating speed of the sheet transfer mechanism is regulated so that the pusher elements do not re-engage the sheet at the assembly station B to advance the same until the bonding operation is completed and the pressure arm 66 is released.

In order to accommodate the use of cover elements of varying length and to permit attachment of the cover elements at different predetermined locations on the sheet, several adiustrnents are provided. Referring to Figs. 1 and 3, the table 12 which supports the unit 11 is in this case mounted by the wheels 13 on a track 14 so as to be movable relative to the unit 19. A pair of brackets 111 and 112 are rigidly secured to the table 12 and to the bed 21 of the unit 19, respectively, and an adjustable turn buckle device 113 pivotally interconnects the brackets 111 and 112 so that by adjustment of the turn buckle device the unit 11 can be moved closer to or farther from the unit 19. Also, the pressure applying mechanism 63 at the assembly station B is adjustable along the edge of the bed 21 to permit bonding of the cover elements at different predetermined locations along the edges of the sheets. For this purpose, the lower beam 64 is supported for adjustable movement longitudinally of the bed 21 on a base 114 (Fig. 6) which has an elongated slot 116, the beam 64- being secured in any desired adjusted location by means of bolts 117 (Fig. 7) extending through the slot 116.

A complete operation on one sheet will now be described for a further understanding of the invention. Referring particularly to Figs. 6 and 7, at assembly station B a sheet 118 has been moved into selected position beneath the pressure arm 66 for application of a cover element near the left-hand corner of the sheet as viewed in Fig. 6. The pushers 42 are at the right-hand of their travel along the bed 21 and are about to be retracted beneath the bed for movement to the left-hand end of the stroke of the sheet transfer mechanism. Since the sheet transfer mechanism has completed one cycle, the feeder unit 16 has been actuated through 102-403 to feed another sheet to the delivery station A for the next operation and at the same time the strip former and feeder unit 11 has been actuated through 103-404-406 1 7108 to advance the strip 27 one predetermined increment toward the assembly station B. As this movement of the strip occurs, the terminal cover element designated at 119 leaves the guide member 56 and is positioned in registered location on the edge of the sheet 118. Since the sheet transfer mechanism is at the right-hand end of its stroke, the pressure applying mechanism 63 is actuated by tripping of the limit switch 109 as previously described. The terminal cover element 119 is thereby bonded under heat and pressure to the sheet 118 and at the same time the connecting portion 31 between the terminal cover element 119 and the next adjacent cover element on the strip is severed by the knife blade 76. Of course, a snug fit of the terminal cover element 119 against the edge of the sheet 118 is insured by the action of the bacleup roller 77 and the pusher member 82 as hereinbefore described.

fter the platen 73 has remained in clamping position for the required time as controlled by the time delay relay control for the piston and cylinder means 71, the arm 66 of the press is released so that the sheet 118 with its attached individual cover element 119 is ready to be transferred to the next stage of the operation. 9 shows the condition of the sheet at this point with the element 119 permanently bonded to the original edge 121 of the sheet 118. It will be noted that the inner corners of the applied cover element are rounded, as at 32, by reason of the precut configuration of the strip 27. Moreover, the outer corners of the applied cover element have extending therefrom the residual fragments 31a of the severed connecting portions 31. Also, as previously men- 9 tioned the cutting action of the knife blade 76 in severing the terminal cover element from the strip results in a corresponding slit 122 in the edge of the sheet 113.

At this point the sheet transfer mechanism has now completed its leftward movement, as viewed in Fig. 6, and the pushers 42 are again projected upwardly through the bed 21 into transfer position whereupon the sheet 118 with attached cover element 119 is moved along the bed 21 to the right to station C. As the sheet transfer mechanism reaches the right-hand end of its stroke, the

die-cutting means 91 is automatically actuated to trim away the longitudinal edge portion of the sheet and form a tab thereon in the region of the cover element 119. Fig. illustrates the condition of the sheet following this stage of the process. It will be seen that the edge of the sheet 118 itself has been cut off together with a selected portion of the cover element 119 so as to form a new longitudinal edge 123 with a round cornered projecting covered tab portion 124. The portions of the sheet 118 and cover element 119 which are removed in the die-cutting operation at station C are shown in broken lines in Fig. 10. I

Upon the next cycle of the sheet transfer mechanism the completed sheet 118 with its covered index tab 124 is shifted to station D and thence discharged from the bed 21.

Although the invention has been described with reference to a particular structural embodiment thereof, it is to be understood that various modifications and equivalent arrangements may be used without departing from the scope of the invention as defined in the appended claims.

I claim:

1. The method of providing index tabs on sheets which comprises the steps of aligning an elongated longitudinally prefolded cover strip in straddled relation over the edge of a sheet, applying pressure to the end portion of the aligned strip for bonding the same to the sheet, severing said end portion from the remainder of the strip, and thereafter cutting the strip portion attached to the edge of the sheet to provide a projecting tab of desired shape.

2. The method of claim 1 further characterized in that said cover strip comprises a plastic material having a heat activatable adhesive coating and the end portion of said strip is bonded to said sheet by application of heat and pressure.

3. The method of claim 1 further characterized by the additional step of laterally urging the sheet and the strip toward each other prior to the application of bonding pressure to the strip.

4. The method of providing index tabs on sheets which comprises the steps of aligning an elongated longitudinally prefolded cover strip in straddled relation over the edge of a sheet, applying pressure to the leading end portion of the aligned strip for bonding the same to the sheet and simultaneously severing said end portion from the remainder of the strip to leave a separate cover element attached to the sheet, and thereafter cutting the attached cover element to provide a projecting tab of desired shape. 5. The method of forming covered index tabs on sheets which comprises the steps of folding an elongated strip of tab covering material longitudinally, cutting the folded strip at longitudinally spaced intervals with incomplete transverse cuts extending partially across the width of the strip from the open edge thereof toward the folded edge thereof whereby to provide a plurality of folded cover elements interconnected in end-to-end relation by restricted uncut connecting portions along the folded edge of the strip, feeding the preformed strip longitudinally and aligning the terminal cover element at the leading end of the strip in straddled relation over the edge of a sheet, applying pressure to said terminal cover element for bonding the same to the sheet, cutting the adjacent connecting portion whereby to sever the terminal cover element from the remainder of the strip, and thereafter 10 cutting the edge of the sheet to form a new edge with a covered tab projecting outwardly therefrom.

6. The continuous method of forming covered index tabs on sheets which comprises the steps of feeding sheets one-by-one to an assembly station, simultaneously feeding to said assembly station in stepwise increments and in timed relation with said sheets a continuous longitudinally folded cover strip, aligning the leading end por tion of said strip in straddled relation over the edge of the sheet at said assembly station, applying pressure to said leading end portion for bonding the same to the sheet and severing said leading end portion from the remainder of the strip to leave a separate cover element attached to the edge of the sheet, and thereafter moving the sheet with its attached cover element to a tab-forming station and cutting the edge of the sheet to form a new edge with a covered tab projecting outwardly therefrom.

7. The continuous method of forming covered index tabs on sheets which comprises the steps of forming a continuous longitudinally folded cover strip with incomplete transverse cuts extending partially across the width of the strip to provide a plurality of folded cover elements interconnected in end-to-end relation by restricted uncut connecting portions along the folded edge of the strip, feeding sheets one-by-one to an assembly station, simultaneously feeding said strip to said assembly station in stepwise increments and in timed relation with the sheets, aligning the terminal cover element at the leading end of the strip in straddled relation over the edge of the sheet at said assembly station, applying pressure to said terminal cover element for bonding the same to the sheet and cutting the adjacent connecting portion whereby to sever the terminal cover element from the remainder of the strip, and thereafter moving the sheet with its attached cover element to a tab-forming station and cutting the edge of the sheet to form a new edge with a covered tab projecting outwardly therefrom.

8. The method of claim 7 further characterized in that the aligning of said strip with the sheet is accomplished by continuously spreading apart the folded halves of the strip at the leading end thereof as the strip is fed longitudinally to the assembly station, moving the edge of the sheet longitudinally into register between the spread apart halves of the strip, and releasing the spread apart halves so as to embrace the edge of the sheet at a predetermined location longitudinally thereof.

9. The continuous method of forming covered index tabs on sheets which comprises the steps of feeding a plurality of horizontally disposed sheets one-by-one to an assembly station, feeding an elongated longitudinally folded cover strip in the same general direction as the sheets in successive steps and in timed relation'with the sheets, the open edge of the folded strip facing a longitudinal edge of the sheet for receiving the latter, registering the leading end portion of the strip in straddled relation and parallel alignment with respect to the longitudinal edge of each successive sheet at the assembly station, applying pressure to the registered leading end portion of the strip for bonding the same to the sheet and severing said leading end portion from the remainder of the strip to provide a separate cover element attached to the sheet, and successively moving each sheet with its attached cover element to a tab-cutting station and cutting the edge of the sheet to form a new edge with a covered tab projecting outwardly therefrom.

10. Apparatus for continuously forming covered index tabs on sheets including an assembly station and a tab cutting station, means for feeding sheets one-by-one to said assembly station, means for feeding an elongated longitudinally folded cover strip to said assembly station in timed relation to the feeding of the sheets, guide means for registering the leading end portion of the strip in straddled relation with the edge of the sheet in position at the assembly station, movable pressure applying means at said assembly station engageable with the aligned leading end portion of the strip for bonding the same to the sheet, means movable in response to operation of said pressure applying means for severing the leading end portion of the strip from the remainder of the strip thereby providing the sheet with a separate co-ver element attached to the edge thereof, means for moving each sheet with its attached cover element from said assembly station to said tab cutting station, and means at said tab cutting station for cutting the edge of the sheet to form a new edge with a covered tab projecting outwardly therefrom.

11. The apparatus of claim further characterized in that said pressure applying means includes a movably mounted platen with means for moving the same into and out of clamping engagement with the leading end portion of the strip at selected intervals, and said means for severing the leading end portion of the strip comprises a blade carried by said platen and extending transversely of the strip for severing the leading end portion thereof when said platen engages the strip.

12. The apparatus of claim 10 further characterized in that said pressure applying means includes a pair of heated platens at least one of which is movable toward and away from the other for clamping the leading end portion of the strip therebetween and thereby bonding the same to the sheet under heat and pressure.

13. The apparatus of claim 10 further characterized in that alignment means is provided at said assembly station cooperable with the sheet and the strip for urging the same laterally toward each other whereby to insure snug parallel contact between the edge of the sheet and the inside of the folded edge of the strip prior to the application of bonding pressure thereto.

14. The apparatus of claim 13 further characterized in that said alignment means comprises a pusher element carried by the movable pressure applying means for urging the sheet and the strip into said snug contact just before engagement of the pressure applying means with the strip.

15. The apparatus of claim 13 further characterized in that said alignment means comprises an adjustable bacl:up member mounted for engagement with the outside of the folded edge of the strip and a pusher member carried by the movable pressure applying means for frictionally engaging the sheet and urging the same laterally toward said back-up member and into snug contact with the inside of the folded edge of the strip just before engagement of the pressure applying means with the strip.

16. Apparatus for continuously forming covered index tabs on sheets comprising an elongated horizontal bed having arranged thereon in the named order a receiving station at one end, an assembly station, a tab cutting station, and a discharge station at the opposite end; sheet feeding mechanism for delivering horizontally disposed sheets one-by-one to said receiving station; sheet moving means on said bed for moving the sheets successively in intermittent steps from said receiving station to said assembly station, then to said tab cutting station, and finally to said discharge station; cover strip feeding means for feeding an elongated longitudinally folded and horizontally disposed cover strip toward said assembly station in the same general direction as and in timed relation to the movement of the sheets with the open edge of the folded strip facing the adjacent longitudinal edges of the sheets for receiving the latter; stationary guide means mounted adjacent said assembly station for converging the strip with the sheets and registering the leading end portion of the advancing strip in straddled relation over the edge of each successive sheet; pressure applying means at said assembly station including a stationary platen and a movable platen adapted to clamp the leading end portion of the strip therebetween for bonding the same to the sheet at the assembly station, said movable platen being mounted at the upper side of the bed and carrying a cutting element extending transversely of the strip for severing the leading end portion thereof simultaneously with the clamping action between said platens whereby to provide each sheet with a separate cover element attached to the edge thereof; die-cutting mechanism at said tab cutting station for cutting the edge of each sheet with its attached cover element whereby to form a new edge with a covered tab projecting outwardly therefrom; and actuating means for operating said movable platen and said die-cutting mechanism in response to movement of sheets to said assembly station and to said tab cutting station by said sheet moving means.

17. Apparatus for continuously forming covered index tab on sheets, comprising an assembly station; cover strip forming and feeding mechanism including folded means for longitudinally folding an elongated strip of tab covering material, die-cutting means for cutting the folded strip at longitudinally spaced intervals with incomplete transverse cuts extending partially across the width of the strip from the open edge thereof to the folded edge thereof to provide a plurality of folded cover elements having rounded corners and interconnected in end-to-end relation by restricted uncut connecting portions along the folded edge of the strip, and means for feeding the resultant strip in stepwise increments to said assembly station; sheet feeding means for feeding a plurality of sheets one-by-one to said assembly station; means for actuating said cover strip forming and feeding mechanism and said sheet feeding means in synchronized relation so that each incremental advance of said strip is in timed relation to the feeding of one of said sheets; means for aligning the terminal cover element at the leading end of the strip in straddled relation over the edge of a sheet at said assembly station; pressure applying means at said assembly station including a movable pressure member engageable with said terminal cover element for permanently bonding the latter to the sheet; cutting means operable in conjunction with said movable pressure member for cutting the connecting portion ad jacent said terminal cover element whereby to sever the latter from the remainder of the strip; a tab forming station longitudinally removed from said assembly station; movable die-cutting mechanism at said tab forming station for trimming the edge of the sheet with its attached cover element to form a new edge with a covered tab projecting outwardly therefrom; sheet transfer means for transferring successive sheets to said assembly station and from said assembly station to said tab-forming sta tion; and actuating means for operating said movable pressure member and said movable die-cutting mechanism in response to movement of the sheets by said sheet transfer means.

18. In an apparatus of the class described for applying a folded cover element to the edge of a sheet, the combination of means for feeding a sheet, means for feeding a folded cover element in the same general direction as the sheet with the open edge of the cover element facing the edge of the sheet, and guide means for registering the cover element in straddled relation over the edge of the sheet, said guide means comprising an elongated guide member having a laterally disposed generally U-shaped cross-section with transversely spaced upper and lower wall portions, the sheet feeding means being arranged to deliver a sheet into the space between said wall portions at one end of said member, and generally pointed spreader means extending angularly from said member at said one end thereof and adapted to extend in between and to spread apart the folded halves of the cover element in response to feeding of the latter against said spreader means, said spreader means merging with said spaced wall portions at said one end of the guide member whereby movement of the spread apart cover element along said member causes the respective halves of the cover element to straddle the exterior of said spaced wall portions and continued feeding of the' spread apart cover element beyond the opposite end of said member causes the cover element to embrace the edge of the sheet in straddled relation thereon.

19. The apparatus of claim further characterized in that said guide means comprises an elongated stationary guide member having transversely spaced upper and lower wall portions adapted to receive the sheet therebetween at the assembly station, and a spreader at one end of the guide member for extending between the folded halves of the cover strip at the leading end thereof and continuously spreading apart the strip in response to feeding movement of the strip whereby the spread apart strip straddles the exterior of said wall portions and subsequently embraces the edge of the sheet in predetermined straddled location thereon as the sheet and the leading end portion of the strip are fed beyond the opposite end of said guide member.

20. The apparatus of claim 10 further characterized in that an adjustable connection is provided between the strip feeding means and said assembly station whereby to regulate the distance therebetween for application of tab covers of different lengths.

21. The apparatus of claim 10 further characterized in that said pressure applying means is adjustable longitudinally of the assembly station for varying the location of the cover element along the edge of the sheet.

22. The method of providing index tabs on sheets which comprises the steps of folding an elongated strip of tab covering material longitudinally, cutting the folded strip at longitudinally spaced intervals with incomplete transverse cuts extending partially across the width of the strip from the open edge thereof toward the folded edge thereof whereby to provide a plurality of folded cover elements interconnected in end-to-end relation by restricted uncut connecting portions along the folded edge of the strip, feeding the preformed strip longitudinally and aligning the terminal cover element at the leading end of the strip in straddled relation over the edge of a sheet, applying pressure to said terminal cover element for bonding the same to the sheet, cutting the adjacent connecting portion whereby to sever the terminal cover element from the remainder of the strip, and thereafter cutting the cover element attached to the edge of the sheet to provide a projecting tab of desired shape.

23. The continuous method of'providing index tabs onsheets which comprises the steps of forming a continuous longitudinally folded cover strip with incomplete transverse cuts extending partially across the width of the strip to provide a plurality of folded cover elements interconnected in end-to-end relation by restricted uncut connecting portions along the folded edge of the strip, feeding sheets one-by-one to an assembly station, simultaneously feeding said strip to said assembly station in stepwise increments and in timed relation with the sheets, aligning the terminal cover element at the leading end of the strip in straddled relation over the edge of the sheet at said assembly station, applying pressure to said terminal cover element for bonding the same to the sheet and cutting the adjacent connecting portion whereby to sever the terminal cover element from the remainder of the strip, and thereafter moving the sheet with its attached cover element to a tab-forming station and cutting the attached cover element to provide a projecting tab of desired shape.

24. The method of forming covered index tabs on sheets which comprises the steps of aligning an elongated longitudinally prefolded cover strip in straddled relation over the edge of a sheet, applying pressure to the end portion of the aligned strip for bonding the same to the sheet, laterally urging together the sheet and the strip for insuring snug contact between the edge of the sheet and the inside of the folded edge of the cover strip prior to the application of pressure, severing said end portion from the remainder of the strip, and thereafter cutting the edge of the sheet to form a new edge with a covered tab projecting outwardly therefrom.

25. Apparatus for continuously providing index tabs on sheets including an assembly station and a tab cutting station, means for feeding sheets one-by-one to said assembly station, means for feeding an elongated longitudinally folded cover strip to said assembly station in timed relation to the feeding of the sheets, guide means for registering the leading end portion of the strip in straddled relation with the edge of the sheet in position at the assembly station, movable pressure applying means at said assembly station engageable with the aligned leading end portion of the strip for bonding the same to the sheet, means movable in response to operation of said pressure applying means for severing the leading end portion of the strip from the remainder of the strip thereby providing the sheet with a separate cover element attached to the edge thereof, means for moving each sheet with its attached cover element from said assembly station to said tab cutting station, and means at said tab cutting station for cutting the attached cover element to provide a projecting tab of desired shape.

26. The apparatus of claim 25 further characterized in that alignment means is provided at said assembly station cooperable with the sheet and the strip for urging the same laterally toward each other prior to the application of bonding pressure thereto.

27. The apparatus of claim 25 further characterized in that said guide means comprises an elongated stationary guide member having transversely spaced upper and lower wall portions adapted to receive the sheet therebetween at the assembly station, and a spreader at one end of the guide member for extending between the folded halves of the cover strip at the leading end thereof and continuously spreading apart the strip in response to feeding movement of the strip whereby the spread apart strip straddles the exterior of said wall portions and subsequently embraces the edge of the sheet in predetermined straddled location thereon as the sheet and the leading end portion of the strip are fed beyond the opposite end of said guide member.

References Cited in the file of this patent UNITED STATES PATENTS 

